JP2016130545A - Insulation bearing - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an insulation bearing that hardly causes creeping discharge and has high-reliability under a high-voltage environment.SOLUTION: In the insulation bearing in which an insulation layer (4) is formed in at least one of an outer ring (2) and an inner ring, at least one of the outer ring (2) and the inner ring includes a step part (10). In the insulation bearing, the insulation layer (4) is formed at whole surface of the step part (10).SELECTED DRAWING: Figure 1

Description

  The present invention applies a voltage to the bearing, such as a bearing used in a general industrial electric motor, an electric motor for a vehicle mounted on a train / electric vehicle / hybrid car, etc., a generator, a speed increaser for a windmill, etc. The present invention relates to an insulated bearing used in an environment in which a current may flow inside the bearing.

  In general, it is known that when a current flows in the bearing, electrolytic corrosion occurs even if the current is small, and the life of the bearing is significantly shortened. Therefore, there is a possibility that a current flows inside the bearing, such as a bearing used for a general industrial electric motor, an electric motor for a vehicle mounted on a train / electric car / hybrid car, a generator, a speed increaser for a windmill, etc. Conventionally, a bearing used in a certain environment has been formed by forming an insulating layer on at least one of an inner ring and an outer ring to prevent current from flowing.

  As an example, Patent Documents 1 and 2 describe an insulating bearing 50 as shown in FIG. In FIG. 5, 1 is an inner ring, 2 is an outer ring, 3 is a ball that is a rolling element, 5 is a cage, 6 is a rolling surface, and the ball 3 is disposed so as to contact the rolling surface 6. The outer ring 2 is formed with an insulating layer 4 made of ceramic on the outer peripheral surface 12 and the axial end surface 13, and the outer ring 2 is in contact with the housing 40 fixed to the stator or the like of the electric motor via the insulating layer 4. Yes. With such a configuration, the insulated bearing 50 shown in FIG. 5 insulates the outer ring 2 and the housing 40 from each other and prevents current from flowing inside the bearing.

Patent Document 3 describes an insulating bearing 60 as shown in FIG. In FIG. 6, 1 is an inner ring, 2 is an outer ring, 3 is a ball that is a rolling element, 6 is a rolling surface, and the ball 3 is disposed so as to be in contact with the rolling surface 6. A step portion 9 is provided between the inner peripheral surface 11 and the axial end surface 13 of the outer ring 2. The step portion 9 includes a surface 14 parallel to the axial direction and a surface 15 parallel to the radial direction.
An insulating layer 4 made of hard rubber is formed on the outer circumferential surface 12 of the outer ring 2, the axial end surface 13, and the surface 14 parallel to the axial direction of the stepped portion 9, and the outer ring 2 is connected to the outer ring 2 via the insulating layer 4. The housing 40 is in contact.
With such a configuration, the insulated bearing 60 described in FIG. 6 prevents the current from flowing inside the bearing as in the patent documents 1 and 2, and is parallel to the axial direction of the stepped portion 9. By forming the insulating layer 4 on the surface 14, the insulating layer 4 is prevented from peeling off.

JP-A-1-182621 JP 2004-144184 A Microfilm disclosed in Japanese Utility Model Publication No. 64-38320

  In recent years, as the voltage used in electric devices such as electric motors and generators increases, conventional insulating bearings as described above do not always provide a sufficient insulating effect even if the insulating layer is thickened. I know that there are cases. As a result of a detailed investigation, it has been found that creeping discharge occurs on the surface of the insulating layer formed on the bearing under high voltage conditions, thereby causing current to flow inside the bearing.

  That is, with reference to FIG. 5, when a high potential difference occurs between the insulating bearing 50 and the housing 40, creeping discharge occurs on the surface of the insulating layer 4 formed on the outer ring 2, and the insulating layer in the outer ring 2. It has been found that a current flows between the portion 8 where 4 is not formed and the housing 40. Since the bearing deteriorates rapidly when a current flows inside the bearing, the insulation bearing described in FIG. 5 has a problem that the life may be remarkably shortened when used in a high voltage environment. .

  In addition, the insulating bearing 60 described in FIG. 6 also has only the insulating layer 4 formed on the surface 14 parallel to the axial direction of the stepped portion 9 in order to make it difficult to peel off the insulating layer 4. Therefore, when a high potential difference is generated between the insulating bearing 60 and the housing 40, the surface 15 of the insulating layer 4 between the surface 15 parallel to the radial direction where the insulating layer 4 is not formed and the housing 40. Creeping discharge occurs in the area. Therefore, the insulating bearing described in FIG. 6 also has a problem that the life may be remarkably shortened when used in a high voltage environment as in FIG.

  Therefore, the present invention has been made paying attention to the problems of the conventional insulation bearing described above, and even when used in an environment where a high voltage is applied, creeping discharge hardly occurs in the insulation layer, and the long life is achieved. An object of the present invention is to provide an insulated bearing.

The above-described problem according to the present invention is solved by the following configuration.
(1) In an insulating bearing in which an insulating layer is formed on at least one of the outer peripheral surface of the outer ring and the axial end surface of the outer ring, or the inner peripheral surface of the inner ring and the axial end surface of the inner ring, the inner peripheral surface of the outer ring and the inner ring At least one of the outer ring axial end surface or the inner ring outer peripheral surface and the inner ring axial end surface is provided with a step portion composed of two or more surfaces, and the entire step portion An insulating bearing, wherein an insulating layer is formed.
(2) The insulated bearing according to (1), wherein a total length of the stepped portions is 1 mm or more.
(3) The step (1) or (1) is characterized in that the step portion is constituted by a plane parallel to the axial direction and a plane inclined by an angle θ (0 ° ≦ θ ≦ 45 °) with respect to the radial direction. The insulated bearing as described in (2).
(4) The insulating bearing according to any one of (1) to (3), wherein the insulating layer is a ceramic layer formed by thermal spraying.

The insulating bearing of the above (1) has two or more surfaces between at least one of an inner peripheral surface of an outer ring and an axial end surface of the outer ring or between an outer peripheral surface of the inner ring and an axial end surface of the inner ring. The insulating layer is formed on the entire surface of the step portion.
Therefore, the insulating bearing has a length along the surface of the insulating layer from the portion of the outer ring or inner ring where the insulating layer is not formed to the external member (housing, rotating shaft, etc.) connected to the bearing, that is, the creepage distance. Therefore, creeping discharge hardly occurs on the surface of the insulating layer, and the life of the bearing can be prevented from being shortened by a current derived from the creeping discharge.
Therefore, the insulated bearing of the above (1) has an effect of being highly reliable and having a long life even in an environment where a high voltage is applied.

In addition, since the total length of the stepped portion is 1 mm or more, the insulated bearing of (2) can effectively suppress creeping discharge in the stepped portion, and the outer ring or the inner ring is thin. However, there is an effect that it is highly reliable and has a long life in an environment where a high voltage is applied.
In addition, the insulating bearing of the above (3) is composed of a surface parallel to the axial direction and a surface inclined by an angle θ (0 ° ≦ θ ≦ 45 °) with respect to the radial direction. As the distance increases, the corners do not become acute, and stress and electric field concentration at the corners can be prevented. Therefore, the insulated bearing (3) has an effect that it is more reliable and has a long life under an environment where a high voltage is applied.
Furthermore, since the insulating bearing of the above (4) is a ceramic layer in which the insulating layer is formed by thermal spraying, it is possible to efficiently form a high-quality insulating layer regardless of the size and shape of the bearing. Play.

  The present invention has been briefly described above. Further, details of the present invention will be further clarified by reading a form for carrying out the invention described below (hereinafter referred to as “embodiment”) with reference to the accompanying drawings.

It is sectional drawing which shows the outer ring | wheel of the insulated bearing which concerns on the 1st Embodiment of this invention. It is sectional drawing which shows the step part vicinity in the insulated bearing of FIG. It is a graph which shows the relationship between the total length of a step part, and a creeping discharge voltage. It is sectional drawing which shows the inner ring | wheel of the insulated bearing which concerns on the 2nd Embodiment of this invention. It is sectional drawing which shows the conventional insulated bearing. It is sectional drawing which shows another conventional insulated bearing.

Embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a cross-sectional view showing an outer ring 2 of an insulated bearing 100 according to the first embodiment of the present invention. Here, the same reference numerals are given to the same portions as those in the conventional example.
Referring to FIG. 1, outer ring 2 has rolling surface 6, inner peripheral surface 11, outer peripheral surface 12, and axial end surface 13, and a rolling element (ball) (not shown) is disposed so as to be in contact with rolling surface 6. Is done. Reference numeral 4 denotes an insulating layer formed on the surface of the outer ring 2. The insulating layer 4 will be described in detail later. The outer peripheral surface 12 of the outer ring 2 is in contact with the housing 40 fixed to the stator or the like of the electric motor via the insulating layer 4.
The insulated bearing 100 according to this embodiment includes a step portion 10 between the inner peripheral surface 11 and the axial end surface 13 of the outer ring 2.

FIG. 2 is an enlarged view of a circled portion in FIG. 1, that is, a portion near the stepped portion 10. Here, a broken line shows the outer ring | wheel of the conventional insulated bearing in which the step part 10 is not provided. As shown in FIG. 2, the stepped portion 10 is provided between the inner peripheral surface 11 and the axial end surface 13 of the outer ring 2, and includes a first surface 16 and a second surface 17. The first surface 16 is a surface that extends from the first corner 18 that intersects the axial end surface 13 to the second corner 19 that intersects the second surface 17, and is substantially parallel to the axial direction. The second surface 17 is a surface from the second corner portion 19 to the third corner portion 20 that intersects the inner peripheral surface 11 and is inclined by an angle θ with respect to the radial direction.
In the present embodiment, R chamfering is performed on the first corner 18, but R chamfering may be appropriately performed on the second corner 19 or the third corner 20. It is also possible to adopt other chamfering such as C chamfering instead of R chamfering, or to omit chamfering, but R chamfering may be performed from the viewpoint of preventing electric field concentration at the corners. preferable.

In this embodiment, in addition to the outer peripheral surface 12 and the axial end surface 13 of the outer ring 2, the insulating layer 4 is formed on the entire surface of the stepped portion 10, that is, the first surface 16 and the second surface 17. Yes. The insulating layer 4 is an insulating ceramic, and is formed on the surface of the outer ring 2 by thermal spraying.
As described above, the present embodiment includes the step portion 10 between the inner peripheral surface 11 and the axial end surface 13 of the outer ring 2, and the insulating layer 4 is formed on the entire surface of the step portion 10. 4, the length along the surface of the insulating layer 4 from the third corner portion 20, which is the terminal end portion 4, to the housing 40 in contact with the outer ring 2, that is, the creeping distance is compared with a conventional insulating bearing that does not include the step portion 10 It is getting longer.

That is, in FIG. 2, ignoring errors due to the corner R and the thickness of the insulating layer 4, the creeping distance of the insulating layer 4 from the terminal end of the insulating layer 4 to the first corner 18 is In contrast to the conventional insulated bearing that does not include the stepped portion indicated by the broken line, the outline is c, whereas in the insulated bearing according to the present embodiment indicated by the solid line, the outline is a + b. On the other hand, the creeping distance of the insulating layer 4 in the portion from the first corner 18 to the housing 40 is the same for the conventional and the insulating bearing according to the present embodiment.
Therefore, it is clear that the creeping distance of the insulating layer 4 from the terminal portion of the insulating layer 4 to the housing 40 is longer by about a + bc in the insulating bearing according to the present embodiment than in the conventional one. is there.

In general, when two electrodes are separated via an insulator, creeping discharge generated on the surface of the insulator is less likely to occur as the creepage distance of the insulator between the two electrodes is longer. When this is applied to a bearing having an outer ring formed with an insulating layer, the portion of the outer ring where the insulating layer is not formed and the housing in contact with the outer ring act as both electrodes. As the creepage distance of the insulating layer is longer, creeping discharge is less likely to occur.
As described above, the insulating bearing according to the present embodiment has a creeping distance of the insulating layer 4 between the terminal portion of the insulating layer 4 and the housing 40 that is longer than the conventional one. Compared with that, creeping discharge hardly occurs on the surface of the insulating layer 4.

  The conventional insulating bearing 60 shown in FIG. 6 is intended to solve a problem completely different from the present invention of preventing the peeling of the insulating layer 4, but a step portion similar to the step portion 10 of the present embodiment. 9 is formed. However, in the insulating bearing 60 of FIG. 6, the insulating layer 4 is formed only on the surface 14 parallel to the axial direction of the stepped portion 9, and the insulating layer 4 is not formed on the surface 15 parallel to the radial direction. That is, in the insulating bearing 60, the insulating layer 4 is merely formed in the step portion 9 by a length corresponding to the length b shown in FIG.

On the other hand, in the insulating bearing 100 according to the present embodiment, the insulating layer 4 is formed on the entire surface of the step portion 10. Therefore, since the length of the portion where the insulating layer 4 is formed in the step portion 10 of the insulated bearing 100 according to the present embodiment is approximately a + b, the insulated bearing 100 according to the present embodiment is the insulated bearing 60 of FIG. In comparison with the above, the creeping distance of the insulating layer 4 to the end portion of the insulating layer 4 and the housing 40 is approximately a (= a + b−b).
Therefore, it is obvious that the creeping discharge is less likely to occur in the insulated bearing 100 according to the present embodiment than that described in FIG. Thus, the present embodiment has a remarkable effect in terms of preventing creeping discharge even when compared with that described in FIG.

  As described above, the insulating bearing 100 according to this embodiment has a creepage distance of the insulating layer 4 that is longer than that of the conventional bearing, and can make creeping discharge less likely to occur. Therefore, the insulated bearing 100 according to the present embodiment is less likely to flow current due to creeping discharge inside the bearing than the conventional bearing, and is used without deterioration for a long time even in an environment where high voltage is applied. can do.

Here, the outer ring 2 is reduced in thickness so that the first corner 18 is very close to the housing 40, and the total length of the stepped portion 10, that is, a + b, and creeping discharge occurs in the stepped portion 10. FIG. 3 shows the results of experiments conducted on the relationship with voltage (hereinafter referred to as “creeping discharge voltage”).
As can be seen from FIG. 3, a + b and the creeping discharge voltage have a positive linear relationship, and the creeping discharge voltage increases as a + b increases. In an actual bearing, the value of a + b may be appropriately designed according to the size of the bearing, the voltage level applied to the bearing, and the like.

Referring to FIG. 2 again, in the present embodiment, the second surface 17 is configured to be inclined by an angle θ with respect to the radial direction. The angle θ depends on the width of the outer ring and the bearing. It can be appropriately selected according to the voltage level or the like.
If the second surface 17 is parallel to the radial direction, that is, if θ is 0 degree or more, including the case where θ = 0 degree, the angles of the second corner part 19 and the third corner part 20 (subordinate angle) Is not an acute angle, and a decrease in strength due to stress concentration at these corners is avoided, and electric field concentration at these corners is also alleviated, so that θ is preferably 0 ° or more. Further, if θ is made larger, it is more preferable from the above viewpoint, but if θ is made too large, the second corner portion 19 approaches the first corner portion 18 side, and accordingly, the insulating layer in the step portion 10. The creepage distance of 4 becomes short, which is not preferable.
From the above points, θ is preferably in the range of 0 ° ≦ θ ≦ 45 °.

Next, a second embodiment of the present invention will be described with reference to FIG.
FIG. 4 is a cross-sectional view showing the inner ring 1 of the insulated bearing 110 according to the second embodiment of the present invention. This embodiment is different from the first embodiment in that an insulating layer 4 and a stepped portion 10 are provided on the inner ring 1 of the insulating bearing 110. Referring to FIG. 4, inner ring 1 has rolling surface 25, outer peripheral surface 22, inner peripheral surface 23, and axial end surface 24, and a rolling element (ball) (not shown) is disposed so as to be in contact with rolling surface 25. Is done. Reference numeral 4 denotes an insulating layer formed on the surface of the inner ring 1. An inner peripheral surface 23 of the inner ring 1 is in contact with a shaft 41 fixed to a rotor or the like of an electric motor via an insulating layer 4.

A step portion 10 is provided between the outer peripheral surface 22 of the inner ring 1 and the axial end surface 24. The step portion 10 has the same shape as that of the first embodiment shown in FIG. 2 and includes a first surface 27 and a second surface 28. The first surface 27 is a surface that extends from the first corner portion 29 that intersects the axial end surface 24 to the second corner portion 30 that intersects the second surface 28, and is substantially parallel to the axial direction. The second surface 28 is a surface extending from the second corner portion 30 to the third corner portion 31 intersecting with the outer peripheral surface 22 and is inclined by an angle θ with respect to the radial direction.
In this embodiment, in addition to the inner peripheral surface 23 and the axial end surface 24 of the inner ring 1, the insulating layer 4 is formed on the entire surface of the stepped portion 10, that is, the first surface 27 and the second surface 28. ing. The insulating layer 4 is an insulating ceramic and is formed on the surface of the inner ring 1 by thermal spraying.

  By adopting such a configuration, the insulating bearing 110 according to the present embodiment has a creeping distance of the insulating layer 4 from the terminal end of the insulating layer 4 to the shaft 41 as in the first embodiment. Compared to an insulated bearing that does not have a stepped portion, and an insulating bearing that has a stepped portion but has an insulating layer formed only on the surface parallel to the axial direction of the stepped portion (first surface). Yes.

Therefore, the insulating bearing 110 according to the present embodiment is less likely to cause creeping discharge than the conventional bearing, so that current caused by the creeping discharge is less likely to flow inside the bearing, and even under an environment where high voltage is applied, Can be used without long-term deterioration.
Note that it will be apparent to those skilled in the art that the same matters as in the first embodiment described above hold true for the size of a + b and the size of θ in this embodiment as well.

  As mentioned above, although embodiment of this invention has been explained in full detail using drawing, the said embodiment is only a mere illustration, This invention is not limited to embodiment mentioned above, A deformation | transformation is carried out suitably. Improvements are possible. In addition, the material, shape, dimensions, number, arrangement location, and the like of each component in the above-described embodiment are arbitrary and are not limited as long as the present invention can be achieved.

For example, in each embodiment, the insulating layer is a ceramic formed by thermal spraying, but other insulating materials may be used, and the ceramic may be formed by a method other than thermal spraying.
In each embodiment, one of the outer ring or the inner ring includes a stepped portion and an insulating layer, but both the inner ring and the outer ring may include a stepped portion and an insulating layer. Reliability in the environment can be further improved.

Moreover, in each embodiment, although the step part is comprised by two surfaces, you may make it form in three or more surfaces. The shape of each surface constituting the step portion may be either a flat surface or a curved surface, and the surface thereof may be flat, rough, or provided with minute irregularities. It is obvious to those skilled in the art that there is no problem in solving the problem.
Furthermore, although balls are used as rolling elements in each embodiment, the present invention is not limited to this, and the present invention can be widely applied to various bearings such as cylindrical roller bearings, tapered roller bearings, and self-aligning roller bearings.

  The present invention applies a voltage to the bearing, such as a bearing used in a general industrial electric motor, an electric motor for a vehicle mounted on a train / electric vehicle / hybrid car, etc., a generator, a speed increaser for a windmill, etc. The present invention can be suitably used for an insulated bearing used in an environment where current may flow inside the bearing.

DESCRIPTION OF SYMBOLS 1 Inner ring 2 Outer ring 3 Ball 4 Insulating layer 5 Cage 6 Rolling surface 8 Part in which the insulating layer is not formed 9 Step part 10 Step part 11 Inner peripheral surface 12 Outer peripheral surface 13 Axial end surface 14 A surface 15 parallel to the axial direction Surface 16 parallel to radial direction First surface 17 Second surface 18 First corner 19 Second corner 20 Third corner 22 Outer peripheral surface 23 Inner peripheral surface 24 Axial end surface 25 Rolling surface 27 First surface 28 Second surface 29 First corner 30 Second corner 31 Third corner 40 Housing 41 Shaft 50 Conventional insulated bearing 60 Conventional insulated bearing 100 First embodiment of the present invention Insulated bearing 110 according to the present invention Insulated bearing according to the second embodiment of the present invention

Claims (4)

  In an insulating bearing in which an insulating layer is formed on at least one of the outer peripheral surface of the outer ring and the axial end surface of the outer ring, or the inner peripheral surface of the inner ring and the axial end surface of the inner ring, the inner peripheral surface of the outer ring and the shaft of the outer ring A step portion constituted by two or more surfaces between at least one of the inner ring and an outer peripheral surface of the inner ring and an axial end surface of the inner ring, and the insulating layer is provided on the entire surface of the step portion. Insulated bearing characterized by being formed.   The insulated bearing according to claim 1, wherein a total length of the stepped portions is 1 mm or more.   The said step part is comprised from the surface parallel to the axial direction, and the surface inclined only by angle (theta) (0 degree <= theta <= 45 degree) with respect to radial direction. Insulated bearing.   The insulated bearing according to claim 1, wherein the insulating layer is a ceramic layer formed by thermal spraying.

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